Retailers kicked off 2013 with better-than-expected January sales — but volume isn’t everything.

Big chains like Macy’s, Gap and Nordstrom sailed past Wall Street’s estimates, collectively delivering a 5.8 percent surge in same-store sales, or sales at stores open at least a year.

Nevertheless, analysts who had predicted growth of 3.5 percent noted that the revenue upside came at the expense of profits, as penny-pinching consumers pounced on post-holiday clearances.

Kohl’s reported a 13.3 percent same-store sales gain, blowing past estimates for a 3.1 percent gain. But the middle-market department store left its fourth-quarter profit outlook unchanged — an indicator that business was driven by heavy discounts that sapped margins. Shares of Kohl’s, which had slashed its holiday forecast in December, dipped 1 percent, to $45.81.

Consumers “continue to shop with discipline in the face of a slow economic recovery and new pressures, including recent payroll tax increases,” Target CEO Gregg Steinhafel said yesterday.

A notable exception was Macy’s which, in addition to nearly doubling forecasts with an 11.7 percent same-store sales gain, restored its fourth-quarter earnings guidance after cutting it last month on disappointing December sales.